SOLUTION: Use Substitution to solve the system: -x+y=2 x^2+y^2=20

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Question 816620: Use Substitution to solve the system:
-x+y=2
x^2+y^2=20
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
-x+y=2
x^2+y^2=20
-x+y=2
y=x+2

x^2+y^2=20
substitute y
x^2+(x+2)^2=20
x^2+x^2+4x+4=20
2x^2+4x-16=0
/2
x^2+2x-8=0
x^2+4x-2x-8=0
x(x+4)-2(x+4)=0
(x+4)(x-2)=0
x=-4 or x=2
y=x+2
when x=-4
y=-4+2=-2
(-4,-2)
when x=2
y=2+2=4
(2,4)